We know, by conservation of energy :

Therefore,

Putting given values, we get :

Therefore, the spring be compressed to 6.93 cm to send the ball twice as high.
Hence, this is the required solution.
Answer:
Option A applies.
A. Greater than its escape speed from the mass within the volume
Explanation:
Here it is mentioned that the spherical volume is large enough for the space to be considered as homogeneous. Also, the pressure within the volume is negligible, so that will not result into the re collapse of the Universe. Now as per our knowing, Hubble's Law relates the average speed of the particle to the distance R between the Earth and the particle. So, if the particle's speed is greater than it's escape speed from the mass within the volume, then the Universe is bound to re collapse back again. Option A applies.
Answer:
(a) 8.362 rad/sec
(b) 6.815 m/sec
(c) 9.446 
(d) 396.22 revolution
Explanation:
We have given that diameter d = 1.63 m
So radius 
Angular speed N = 79.9 rev/min
(a) We know that angular speed in radian per sec

(b) We know that linear speed is given by

(c) We have given final angular velocity 
And 
Time t = 63 sec
Angular acceleration is given by 
(d) Change in angle is given by

Here are the answers:
1. False - Molecules is the smallest part of an element that behaves like the element.
2. False - The nucleus contains both protons and neutrons
3. True
4. True
5. A. Nucleus
6. D. Neutron
7. B. Protons and Neutrons
8. C. Electron
9. C. 6
10. C.6
<span>The answer would be convection currents. Convection happens when atoms with a lot of heat energy in a liquid or gas transfer and get the room of particles with fewer heat energy. Heat energy is transported from hot places to cooler places by convection.</span>